1. Field of the Invention
The present invention relates to the use of substances which are agonists of a receptor associated with a chlorine channel in a cosmetic and/or dermatological composition, in particular for the purpose of treating wrinkles and fine lines of the skin, and to cosmetic and/or dermatological compositions which contain such a substance.
2. Discussion of the Background
Women, and indeed even men, are currently inclined to wish to appear young for as long as possible and consequently are looking to soften the signs of ageing of the skin, which are reflected in particular by wrinkles and fine lines. In this respect, advertising and fashion present products intended to retain a radiant and wrinkle-free skin, these being the signs of young skin, for as long as possible, all the more so since physical appearance has an effect on mental attitude and/or on morale. It is consequently important to feel physically and spiritually young.
Until now, wrinkles and fine lines have been treated using cosmetic products containing active agents which act on the skin, for example by moisturizing it or by improving its cell renewal or alternatively by promoting the synthesis of collagen of which the cutaneous tissue is composed. However, to date, it is not known to act on wrinkles by involving the muscle components present in the skin.
It is known that the platysma muscles of the face are under the control of the motor nerve afferent activity of the facial nerve and that, moreover, the interlobular septa of the hypoderm contain within them fibers which constitute a striated muscle tissue (panniculus carnosus). Moreover, it is also known that a subpopulation of fibroblasts of the dermis, known as myofibroblasts, has characteristics in common with the muscle tissue.
The Applicants have observed, in certain pathological and therapeutic situations, the role played, as regards the wrinkles of the face, by the nerves controlling all this muscle tissue. Thus, in attacks on the facial nerve, in which transmission of the nerve impulse is interrupted and/or weakened, a paralysis of the muscles of the face is witnessed in the area of innervation. This facial paralysis is reflected, among other clinical indications, by an alleviation in, indeed disappearance of, the wrinkles.
On the other hand, in muscle hypercontraction conditions of the face, the Applicants have observed an accentuation in the wrinkles of the face. Moreover, an accentuation in the wrinkles of the face has also been observed in muscle hypertonia conditions of Parkinson's disease and side-effects induced by neuroleptics.
Moreover, it has been shown that botulinus toxin, originally used for treating spasms, could have an effect on muscle spasticity conditions (see A. Blitzer et al., Arch. Otolaryngol. Head Neck Surg., vol 119, pages 1018 to 1022 (1993)) and on the wrinkles of the glabella, which are intersuperciliary wrinkles (see J. D. Carruters et al., J. Dermatol. Surg. Oncol., vol. 18, pages 17 to 21 (1992)). It is consequently possible, by pharmacological action, to have an effect on the nerve component of wrinkles. Botulinus toxin acts directly at the level of the neuro-muscular junction by blocking the action of acetylcholine on muscular tenseness.
The junction between a nerve and a muscle constitutes the myoneural endplate, before which is found the afferent nerve route known as the motor neuron. Moreover, the cell membranes of each nerve fiber contain many ionic channels, and in particular chlorine channels, capable of allowing the corresponding element to pass through in the ionic form, and, in the case of chlorine channels, in the chloride form. Neuronal receptors are associated with these channels. The neuronal receptors associated with the chlorine channels are in particular receptors for glycine (glycine-strychnine sensitive receptors) and receptors for GABA (GABA.sub.A receptors).
Moreover, it is known that, in the central nervous system, it is possible to decrease the excitability of the neuron by various pharmacological agents which have an effect on the glycine-strychnine sensitive receptors or on the GABA.sub.A receptors of the central nervous system (see W. Sieghart, Trends in Pharmacological Science, vol. 131, pages 446 to 450 (December 1992)). Activation of these receptors opens the chlorine channels and leads to the entry of chloride ions, which results in an increase in the chloride ions in the cells of the nerve fiber and thus to hyperpolarization of the neurons, which consequently become less excitable.
On the other hand, in the neuromuscular junction, a decrease in excitability of the motor neuron leads to a lessened stimulation of the muscle fiber, thus causing it to slacken.
However, to date no completely suitable compositions or methods are available for treating wrinkles and/or fine lines of the skin. Thus, there remains a need for methods and compositions effective for treating wrinkles and/or fine lines of the skin.